C语言中下标与指针的转换以及指向指针的指针的例子

#include <stdio.h> 
 
int main() 
{ 
  int a[3][3] = {{0, 1, 2}, {3, 4, 5}, {6, 7, 8}}; 
  int i = 0; 
  int j = 0; 
 
  for(i = 0; i<3; i++) 
  { 
    for(j=0; j<3; j++) 
    { 
      printf("%d\n", *(*(a+i)+j)); 
    } 
  } 
} 

#include <stdio.h> 
 
int main() 
{ 
  int a = 1; 
  int* p = NULL; 
  int** pp = NULL; 
 
  pp = &p; 
 
  *pp = &a;// ==> p = &a; 
 
  printf("%d", **pp); 
 
  return 0; 
} 

#include <stdio.h> 
 
int reset(char**p, int size, int new_size) 
{ 
  int ret = 1; 
  int i = 0; 
  int len = 0; 
  char* pt = NULL; 
  char* tmp = NULL; 
  char* pp = *p; 
 
  if( (p != NULL) && (new_size > 0)) 
  { 
    pt = (char*)malloc(new_size); 
 
    tmp = pt; 
 
    len = (size < new_size) ? size : new_size; 
 
    for( i=0; i<len; i++) 
    { 
      *tmp++ = *pp++; 
    } 
 
    free(*p); 
    *p = pt; 
  } 
 
  return ret; 
} 
 
int main() 
{ 
  char* p = (char*)malloc(5); 
  printf("%0X\n", p); 
 
  if( reset(&p, 5, 3) ) 
  { 
    printf("%0X\n", p); 
  } 
  return 0;